The present invention relates to polymer compositions and more particularly relates to polymer compositions containing modified pigments and methods of making the same.
U.S. Pat. Nos. 5,559,169 and 5,851,280, incorporated in their entirety by reference herein, describe polymer compositions containing modified carbon products which are useful in a variety of applications, such as plastics, tires, and other polymer goods.
In making the polymer compositions containing the modified carbon products or modified pigments, it would be beneficial if improved methods could be devised to incorporate the modified pigments into the polymer compositions. Typically, modified pigments, such as modified carbon black, are formed in an aqueous solution and this resulting slurry is dried, resulting in a dry modified carbon black. This dry modified carbon black can then be incorporated into polymer compositions and other compositions such as inks and coatings. Thus, substantial cost is incurred in drying the modified carbon black and in redispersing the product in the polymer. Additionally, the modification process results generally in the production of byproducts such as salts which are not readily eliminated from the product.
The disclosed invention allows for a substantially improved and more economical process. The separate drying step for the carbon black may be eliminated. Additionally, the salt associated with the product may be more readily eliminated. Furthermore, the resulting elastomeric compound containing the carbon black and the polymer will not require a separate redispersion step. Also, the elastomeric compound will have a good carbon black dispersion and therefore result in improved properties.
A feature of the present invention is to provide processes for incorporating modified pigments into polymer compositions.
Another feature of the present invention is to provide methods of introducing modified pigments into polymer compositions which result in economical savings as well as reducing the amount of time necessary to prepare polymer compositions containing modified pigments.
Another feature of the present invention is to provide products with superior dispersion of the components.
Another feature of the present invention is to provide products with improved performance.
Another feature of the present invention is to provide products substantially without the associated byproducts.
Additional features and advantages of the present invention will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention. The objectives and other advantages of the present invention will be realized and obtained by means of the elements and combinations particularly pointed out in the written description and appended claims.
To achieve these and other advantages, and in accordance with the purposes of the present invention, as embodied and broadly described herein, the present invention relates to a method of preparing a polymer composition comprising at least one polymer and at least one modified pigment. The method involves introducing at least one slurry containing at least one modified pigment to a polymer solution to form a mixture. The modification of the filler is preferably done in an aqueous medium. At this stage, the polymer solution has not been dewatered. After introducing the slurry, the mixture is then dewatered to form the polymer composition. The polymer solution can be a polymer emulsion, a polymer suspension, or a polymer prepared by free radical polymerization. In addition, polymers prepared by solvent based polymerizations can also benefit from the methods of the present invention.
The present invention also relates to a method of preparing the polymer composition by introducing at least one slurry containing at least one modified pigment to a solution of the precursor of an emulsion polymer. Polymerization of the precursor is then initiated to form a polymer product. This product is then dewatered to form the polymer composition of the present invention.
In another method of preparing the polymer composition, the method involves attaching at least one organic group onto a pigment in the presence of a polymer emulsion to form a polymer product. This product is then dewatered to form the polymer composition of the present invention.
In addition, the present invention relates to a method of forming a polymer composition by attaching at least one organic group onto a pigment in the presence of a quenched and unwashed solution of a polymer prepared by solution or suspension polymerization and solvent. The mixture can then be washed and dewatered to form the polymer composition of the present invention.
In a further method of the present invention, a polymer composition is formed by introducing at least one slurry containing at least one modified carbon black or pigment to a quenched solution of a polymer prepared by solution or suspension polymerization to form a mixture. This mixture is then washed and dewatered to form the polymer composition of the present invention.
In a further method, the filler or pigment can be treated in the aqueous phase of an emulsion or mixture of water and an organic solvent. The modified filler or pigment is then transferred to the organic solvent after treatment. This organic solvent solution can be mixed with the solution of a polymer that is already formed or with the polymer precursor solution. After formation of the polymer, the resulting product can be washed and dewatered.
Finally, the present invention relates to a method of preparing a polymer composition by introducing a modified pigment having attached at least one organic group into a solution containing at least one living polymer. The living polymer can then be terminated by any technique including the option of at least one organic group having a group capable of terminating the living polymer and thus form a polymer composition of the present invention.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the present invention, as claimed.